Physiology of Smooth Muscle Flashcards
Give examples of smooth muscle in in the following systems:
Integumentary (Skin) system
piloerector muscles (Tiny muscles in the skin’s hair follicles that contract, pull the hair upright, and a “goosebump” forms on the skin) - Regulate heat
Give examples of smooth muscle in in the following systems: Eyes
Iris or ciliary body
+ nictitating membrane
Give examples of smooth muscle in in the following systems: Respiratory system
Trachea, bronchi tube, alveolar ducts
Give examples of smooth muscle in in the following systems: Cardiovascular system
Walls of blood vessels
Give examples of smooth muscle in in the following systems: Gastrointestinal system
Walls of organs, ducts of digestive glands
Give examples of smooth muscle in in the following systems: Urinary system
Ureter, bladder, urethra
Give examples of smooth muscle in in the following systems: Reproductive system
Mammary glands, genital ducts, prostate gland, scrotum
Which type of muscle has light/dark bands?
skeletal
Which type of muscle has myofibrils?
skeletal
Which type of muscle has sarcomeres?
skeletal
Which type of muscle has T-tubules?
skeletal
Which type of muscle has an orderly arrangement? Which has a scattered arrangement?
orderly- skeletal
scattered- smooth
Which type of muscle has actin and myosin?
skeletal & smooth
Which type of muscle has troponin?
skeletal
Which type of muscle has tropomyosin?
skeletal & smooth
Which type of muscle has actin?
skeletal & smooth
Which type of muscle has myosin?
skeletal & smooth
Single Unit or Multi Unit?
_______ unit have interconnecting gap junctions;
_______ unit do not.
single ; multi
Single Unit or Multi Unit?
_______ unit have spontaneous contractions ; _______ unit do not.
single ; multi
Single Unit or Multi Unit?
_______ unit have slow wave membrane potential
single
Single Unit or Multi Unit?
_______ unit resemble skeletal muscle
multi
What is the 1st chemical step in smooth muscle contraction?
intracellular Ca2+ increase when Ca2 enters the cell and is released from the sarcoplasmic reticulum.
1) - intracellular Ca2 is increased
What is the 2nd chemical step in smooth muscle contraction?
Ca2+ binds to binds to calmodulin (CaM)
2) Ca2 - calcium binds to CaM
What is the 3rd chemical step in muscle contraction?
Ca2+-calmodulin (CaM) activated myosin light chain kinase (MLCK)
3) Ca2+ CaM activated MLCK
What is the 4th chemical reaction in muscle contraction?
MLCK phosphorylated light chains in myosin head & increases myosin ATPase activity
4) Light chains increase in myosin head & increases myosin ATPase activi
What is the 5th chemical reaction in smooth muscle contraction?
Active myosin crossbridges slide along actin & create muscle tension
5) Myosin crossbridges slide & create tension
What are the 5 simple steps of smooth muscle contraction?
1) intracellular Ca2+ is increased
2) Ca2+ binds to CaM (calmodulin)
3) Ca2+ (+) CaM (switch) activated MLCK
4) Light chains increase in myosin head & increases myosin ATPase activity
5) Myosin crossbridges slide along actin & create tension
What is the 1st chemical reaction of smooth muscle relaxation?
Free Ca2+ in cytosol decreases when pumped out of the cell or back into the sarcoplasmic reticulum
Pump the free Ca2 back in the sarcoplasmic reticulum
What is the 2nd chemical reaction of smooth muscle relaxation?
Ca2+ unbinds from calmodulin
2) Ca2+ unbinds CaM
What is the 3rd chemical reaction in smooth muscle relaxation?
Myosin phosphatase removes phosphate from myosin, decreasing ATPase activity
3) Myosin & phosphate breakup
What is the 4th chemical reaction in smooth muscle relaxation?
Less myosin ATPase results in decreased muscle tension
4) Less myosin ATPase = less tension
What are the three types of action potential (AP) in single unit SM?
1) Spike potential
2) Spike initiated by slow wave
3) Action potential with plateau
What are the two types of AP in Multi unit SM?
Electrical activity initiated by nervous system
Neurotransmitter release
What controls smooth muscle?
Nervous system, humoral control
Which parts of the nervous system control smooth muscle?
sympathetic and parasympathetic nervous systems
What does humoral factors mean when it controls smooth muscle?
hormones and other neurotransmitters reacting to chemicals instead of direct stimulation
What is myosin ATPase in smooth muscle compared to in skeletal muscle?
hydrolysis of ATP
What is the latch bridge mechanism?
Sustained/ prolonged contraction in smooth muscle
What is the nictating membrane in a cat?
The protective structure in the eye, known as the 3rd eyelid. It moves sideways like a windshield wiper.
What does hypocalcemia do to smooth muscle?
It delays contraction
